I have an Extra 300 0.6 with a 14 ounces tank
This tank does not fit alonf the fuselage and it gets tilted, therefore I am Planning to connect two 8-onze tanks but I wonder whether should I do it In pararell (with tee's) or in a serial fashion (one clunk line going in to the other's pressure line)

Hope you can help me out

Sorry to ask...if one tank is not properly secured,,,why would 2 tanks then be properly secured? Maybe I'm not really understanding here, but what I'm reading is your having a problem with a tank moving, or being fastened in the correct place? It would be to your advantage to secure what you have, rather then deal with issues of having 2 tanks now to bounce around. If crutches or foam are needed in fusalage, build/cut to accomodate. There is always a way... good luck.

Well the problem actually is that due to the tank's lenght the 14 ounces doesn't fit in the space between the firewall and the next structural thing.
Therefore what I need is to have a shorter same capacity tank, since there's none complying with this I need to connect two 8 ounces tanks.
My doubt is should I do it in parallel with tee's or should I do it in a serial kind of way that's one hose connects the first tank's clunk, then a second hose goes from that tanks'pressure line to the other's clunk and another hose goes from second tans pressure line to the muffler.
In pararel is by having one tee for the clunks and one tee for the pressure line
Sorry if I wasn't clear enough at the beginning, have a nice one

Serial. If one tank drys up before the next, you'll get air in your fuel line. Bad!

Cheers!

I am running a 14oz and a 6oz tank joined side by side. Simple plumbing along with it. Muffler pressure in one tank, the fuel line out of that tank usually goes to the carb, goes into the pressure line for tank #2 and then out as normal to the carb. Works fine.

No prob niche, sounds like the guys here have some good ideas for you. It's called a simple slave-tank set-up. Heli's use this set-up for consistency of run, or something very similar. I think they use the smaller tank for the feed to the engine, not quite sure though. Your on your way though.

Thank you all for the help
I proceeded to plug the tanks as suggested, tomorrow I'll test them but I know it'll work 'cause you have experience on it
Regards from Bogota, Colombia

Are we discussing gasser tank installation or glow fuel, it looks like you mention a 6.0 engine.

With the gasser you can mount the tank/tanks anywhere you want, preferably on "CG". Gassers require "GAS" fuel tubing and tank stoppers...

The dual tank configuration will work fine, forget the tee'd idea as this is an accident looking to happen. Use the header tank plumbing concept. Essentially tank #1 draws from tank#2. This will work with no issues for either gas or glow.

If you need help with the plumbing schematic just ask.

Either will work fine, just depends what you want to do with it. I've run tanks in series (main tank, header tank) and in parallel (twin 11 oz. saddle tanks in a DF model).

Of course, both have been set up for glow with muffler pressure. The header/master tank's most obvious advantage is the constant pressure the carburator "sees". Even with the twin saddle tanks, the fuel is drawn suprisingly even from both tanks.

If it's gas (with a pump carb), either should probably work okay, though I would tend to lean towards the header/master set up. If you're flying so long that you run the danger of running one tank (saddle set-up) dry, either fly shorter flights or go with the header/master set up.

Sorry for the either/or answer, but I've used both with equal success.
Daren